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4-29-17 version 7.5 Source: Greater New Orleans Expressway Commission A NATURALIST CROSSES LAKE PONTCHARTRAIN By Robert A. (Bob) Thomas, Center for Environmental Communication, School of Mass Communication, Loyola University New Orleans (Certified Master Naturalist, Louisiana Master Naturalists of Greater New Orleans Chapter) – [email protected], 504-865-2107 1 4-29-17 version 7.5 A NATURALIST CROSSES LAKE PONTCHARTRAIN By Robert A. Thomas, Center for Environmental Communication, School of Mass Communication, Loyola University New Orleans (Certified Master Naturalist, Louisiana Master Naturalists of Greater New Orleans Chapter) - [email protected], 504-865-2107 OPENING COMMENTS This adventure began from natural history observations as I drove across the Causeway between Metairie and Mandeville, Louisiana. I was amazed at what a naturalist can see while safely driving at 60 mph, and equally amazed by the number of seemingly simple natural history elements for which I had no explanation. I began making notes and, as a naturalist tends to do, expand my knowledge one step at a time. A host of local naturalists were my main resource, and many of them are mentioned herein. For the most part, the following commentary is based on the near surroundings of the Causeway, but additional Lake Pontchartrain stories are added where relevant. Sorry if your interest is peaked and your drive becomes less relaxing and more observant. In the end, it will be good for you and our beloved lake. All photos by me, unless otherwise credited. THE LAKE’S POINT ORANIZATION The steward of the lake is the Lake Pontchartrain Basin Foundation. Founded in 1989, the LPBF was formed by the Louisiana legislature with the expressed purpose of protecting the quality of the overall watershed. We tend to think about "places" we go, or "where to find a certain species." We need to recalibrate how we view such "places" as components of the ecosystem to which they belong. We talk, as we will generally do below, about our Lake Pontchartrain, but in fact all things natural history are responding more to the entire watershed (ecosystem) instead of just the lake. Remove the watershed, and the lake fails; remove the lake and the estuary to the south will fail. Everything is connected. 2 4-29-17 version 7.5 Map showing the Lake Pontchartrain Basin watershed. Source: Lake Pontchartrain Basin Foundation. Interesting view of most of the watershed of the Lake Pontchartrain Basin, plus the Barataria-Terrebonne Basin on the west side of the Mississippi River. Source unknown. Although we call it the "lake," Lake Pontchartrain is actually an estuarine embayment (that understood, we will call it the “lake” throughout this discussion). It formed 4000 years ago, with the driving forces being 1) down-warping of the surface near the Pleistocene terrace where Mandeville resides today, 2) faulting along the terrace margins, and 3) gradual filling in of the shallow seaward zone to the south as the subdelta formed. The result: an estuary virtually surrounded by land, some from the Pleistocene and some recently laid down by sediment deposit from the Mississippi River, and with openings to the east and rivers flowing in from the north and west. 3 4-29-17 version 7.5 As an estuary, by definition, there is an opening to the salty sea (in this case, the Chef Menteur and Rigolets passes to the east), and freshwater runoff from surrounding lands and inflow from rivers such as the Amite, Blind, Tangipahoa, Tickfaw, Tchefuncte, and the following bayous and their drainages - LaBranche, Lacombe, and Bonfuca/Liberty. Source: NASA. FACTOIDS REGARDING LAKE PONTCHARTRAIN: DEPTH, SALINITIES, AND WIND Size: 40 miles long and 24 miles wide. Average depths are 12-14 ft. The deepest areas are over 80 ft and are located near southshore where they were artificially dredged. Salinities: Freshest to the west, with salinities to the east ranging from 4-10 ppt. There have been years when there were many high saline loving critters in the lake such as sea nettles (Chrysaora quinquecirrha), phosphorus jelly (Mnemiopsis mccradyi), and 4 4-29-17 version 7.5 possibly sea sparkle (Noctiluca scintillans). When the Bonnet Carré Spillway is opened, flooding the lake with an additional 250,000 cubic feet per second of river water, salinities can become very fresh. During those times, aided by freshwater and many nutrients, the estuary can become overridden by algae for a few months, and have large floating mats of water hyacinths (Eichhornia crassipes) and duckweed (Lemna sp.). A careful eye may also see floating carcasses of Nutria and Beaver that drowned in the Bonnet Carré. Southeast winds: Persistent southeast winds push salt water into the Chef Menteur and Rigolets openings from the open Gulf, making the "lake" deeper and more saline (as high as 20 ppt or so). Northwest winds: While southeast winds increase lake salinity, northwest winds have a different effect, especially around New Orleans. Due to the relatively shallow depths of the lake and the far reach over which the winds blow, these winds produce heavy "rollers," wind-blown long waves that push to the southeast. These churn the lake, making it less clear, and are rough on sailboats and other small craft. Shadowing: When winds blow from the north, the trees and buildings of the northshore block or minimizes the winds from the water, so a “shadow-effect” occurs and northshore water is smooth. The farther one goes from northshore, there is a gradual increase is surface turbulence on windy days. On the same day, a naturalist will note driving from south to north that the water is much rougher to the south and gradually becomes smooth to the north. The opposite occurs when the wind comes from the south. LAKEFRONT NEW ORLEANS: ITS FORMATION Throughout most of the 19th Century, the lake was distant in time of travel from the central City. As the 1800s progressed, entertainment facilities flourished at West End. There were outdoor performance stages, restaurants, small beaches, casinos, marinas, and much more. Mass public transportation arriving there began first as a steam engine train that followed the course of the New Basin Canal (now the neutral ground between West End Boulevard and Pontchartrain Boulevard), later replaced by a streetcar. Many people built camps beside or over the water, and its popularity continued for many years. In the early 20th Century, the northshore of the City of New Orleans still ended as a somewhat murky wetland-dominated shoreline. During the heyday of the Works Progress Administration (WPA) period, New Orleans sought to expand and make hospitable new land along the south edge of Lake Pontchartrain. At that time Robert E. Lee Boulevard was the developed limits of the city. In the 1920s, a wall (weir) was constructed in the lake and sand was pumped behind it to create land. By the 1930s, the land was dry enough for construction, so the famous stepped seawall was built on the water’s edge followed by construction of Lakeshore Drive. 5 4-29-17 version 7.5 As World War II approached, much of the new land was leased to the U.S. military for bases that served the war effort. A huge hospital complex was built where UNO now stands. These were entirely gone by the 1960s, but UNO still had a number of Quonset huts and other military buildings. When I taught at UNO in the early 1980s, my classes were held in the “Biology Annex,” a wooden building that was full of termites and the story was that they only reason it didn’t collapse was that the termites were holding hands! After the war, housing development began and today some of the most popular neighborhoods such as Lake Vista and Lakeshore are a major part of the fabric of New Orleans. The zone between the levee and the seawall is the iconic linear park so popular among local citizens. It is a lovely place to visually enjoy Lake Pontchartrain, including an array of animals that inhabit its waters and a nice place to just relax and watch boats sail and motor by. Not too long ago, the seawall was often crowded with people with crab straps catching a nice seafood meal. It is common to see folks fishing there today, and bird watching is great along the seawall. THE CAUSEWAY BRIDGE The Causeway, operated by the Greater New Orleans Expressway Commission, has been listed since 1969 by the Guinness Book of World Records as the World’s longest bridge over water – 23.83 miles. Some think its first place position has been taken by the Jiaozhou Bay Bridge opened in China in 2011, but the length of that bridge does not span entirely over water. The original span is that on the west, opened in 1956. The second, on the east, opened in May 1969. WATER QUALITY Back in the years prior to the 1950s, the lake was used as we use the Florida shores today. It was lined with camps and homes, and there were many businesses there, especially around the New Basin Canal. In fact, there was a train that people took from downtown to the lake to enjoy the entertainment, restaurants, and the water. As the metro area enlarged, the water became contaminated with runoff and sewage. The first no swimming sign appeared in the lake in 1962. In the 1970s and 1980s, the near-shore lake waters were laden with pathogens, and swimmers reported boils and other infections. 6 4-29-17 version 7.5 Source: Lake Pontchartrain Basin Foundation. Mostly due to the public work of the Lake Pontchartrain Basin Foundation, people around the lake began to believe the lake water quality could and should improve.

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